Multiple station turret punch machines such as the Amada Lyla Series Model 50-50-72 can provide up to 72 different punch stations for use in conjunction with a like number of opposing die surfaces. In such a machine, each punch station includes a punch unit and a punch guide. The punch unit includes a punch tip having an edge formed thereon for punching through a metal worksheet. During use, however, the punch tip will become dulled. Rather than disposing of the punch tip and replacing it with a new one, economics have dictated that the punch tip be ground to a new edge and reused.
When grinding a punch tip, however, the overall length of the punch tip will be reduced. Since the distance between the cutting edge of the punch tip and the worksheet constitutes a critical dimension in punching operations, the operator must compensate for the shortened punch tip length.
Punch tips are generally separable from the punch driver body. Therefore, many operators compensate for the shortened punch tip length by placing spacers between the punch tip and the punch driver, thereby increasing the overall length. The accuracy of this time-consuming method will be limited by the available widths of spacer materials. Furthermore, this method may require an undue degree of trial and error before the most nearly correct combination of spacers are discovered.
By another method, the punch assembly has a built-in adjustment plug. Part No. 200213-000, 31/2 stripping guide assembly as manufactured by the Strippit Company represents one such assembly. With these assemblies, however, the operator must make at least two calibration measurements while adjusting the punch tip length. That is, he must measure both the overall length of the punch unit and of the punch assembly. Other disadvantages include the substantial disassembly required to remove the punch tip for sharpening and reinstallment.
Therefore, a need exists for a punch assembly having an adjustable punch head such that punch tip lengths may be easily and accurately adjusted with a minimum of disassembly and by measuring only a single calibration parameter.